(try to) show better diffs

scripts/diff-configs.sh

@@ -14,6 +14,102 @@ BLUE='\033[0;34m'
 YELLOW='\033[0;33m'
 NC='\033[0m' # No Color
 
+# Normalize nix store paths by replacing 32-char hashes with placeholder
+normalize_nix_paths() {
+    sed -E 's|/nix/store/[a-z0-9]{32}-|/nix/store/HASH-|g'
+}
+
+# Filter diff output to remove hunks where only nix store hashes differ
+# Returns: filtered diff (empty if only hash changes), exit code 0 if real changes found
+filter_hash_only_diffs() {
+    local diff_output="$1"
+    local current_hunk=""
+    local output=""
+    local has_real_changes=false
+
+    # Process line by line
+    while IFS= read -r line || [ -n "$line" ]; do
+        if [[ "$line" =~ ^@@ ]]; then
+            # New hunk starts - process previous one if it exists
+            if [ -n "$current_hunk" ]; then
+                if hunk_has_real_changes "$current_hunk"; then
+                    output+="$current_hunk"$'\n'
+                    has_real_changes=true
+                fi
+            fi
+            # Start new hunk
+            current_hunk="$line"$'\n'
+        else
+            # Add line to current hunk
+            current_hunk+="$line"$'\n'
+        fi
+    done <<< "$diff_output"
+
+    # Process last hunk
+    if [ -n "$current_hunk" ]; then
+        if hunk_has_real_changes "$current_hunk"; then
+            output+="$current_hunk"
+            has_real_changes=true
+        fi
+    fi
+
+    # Remove trailing newline
+    output="${output%$'\n'}"
+
+    if [ "$has_real_changes" = true ]; then
+        echo "$output"
+        return 0
+    else
+        return 1
+    fi
+}
+
+# Check if a diff hunk has real changes (not just hash changes)
+hunk_has_real_changes() {
+    local hunk="$1"
+
+    # Use temp file to avoid bash here-string issues
+    local temp_hunk=$(mktemp)
+    printf '%s' "$hunk" > "$temp_hunk"
+
+    local minus_lines=()
+    local plus_lines=()
+
+    # Extract - and + lines (skip @@ and context lines)
+    while IFS= read -r line || [ -n "$line" ]; do
+        if [[ "$line" =~ ^- && ! "$line" =~ ^--- ]]; then
+            minus_lines+=("${line:1}")  # Remove the - prefix
+        elif [[ "$line" =~ ^\+ && ! "$line" =~ ^\+\+\+ ]]; then
+            plus_lines+=("${line:1}")  # Remove the + prefix
+        fi
+    done < "$temp_hunk"
+
+    rm -f "$temp_hunk"
+
+    # If counts don't match, there are structural changes
+    if [ ${#minus_lines[@]} -ne ${#plus_lines[@]} ]; then
+        return 0  # Has real changes
+    fi
+
+    # If no changes at all, skip
+    if [ ${#minus_lines[@]} -eq 0 ]; then
+        return 1  # No real changes
+    fi
+
+    # Compare each pair of lines after normalization
+    for i in "${!minus_lines[@]}"; do
+        local minus_norm=$(echo "${minus_lines[$i]}" | normalize_nix_paths)
+        local plus_norm=$(echo "${plus_lines[$i]}" | normalize_nix_paths)
+
+        if [ "$minus_norm" != "$plus_norm" ]; then
+            return 0  # Has real changes
+        fi
+    done
+
+    # All changes are hash-only
+    return 1
+}
+
 # Check for nvd
 if ! command -v nvd &> /dev/null; then
     echo "Error: nvd not found in PATH"
@@ -205,11 +301,17 @@ for host in $hosts; do
                         echo
                         echo -e "    ${BLUE}▸ $basename${NC}"
 
-                        # If it's a directory, diff key files within it
+                        # If it's a directory, diff all files within it
                         if [ -d "$old_path" ] && [ -d "$new_path" ]; then
-                            # Focus on important files
+                            # Count files to avoid processing huge directories
-                            for pattern in "activate" "etc/*" "*.conf" "*.fish" "*.service" "*.nix"; do
+                            file_count=$(find "$new_path" -maxdepth 3 -type f 2>/dev/null | wc -l)
-                                while IFS= read -r file; do
+
+                            # Skip very large directories (e.g., system-path with 900+ files)
+                            if [ "$file_count" -gt 100 ]; then
+                                echo "      (skipping directory with $file_count files - too large)"
+                            else
+                                # Diff all files in the directory
+                                for file in $(find "$new_path" -maxdepth 3 -type f 2>/dev/null); do
                                     [ -z "$file" ] && continue
                                     relpath="${file#$new_path/}"
                                     old_file="$old_path/$relpath"
@@ -217,16 +319,38 @@ for host in $hosts; do
                                     if [ -f "$old_file" ] && [ -f "$file" ]; then
                                         # Check if file is text
                                         if file "$file" | grep -q "text"; then
+                                            # Get diff output
+                                            diff_output=$(diff -u "$old_file" "$file" 2>/dev/null | head -50 | tail -n +3 || true)
+
+                                            # Filter hash-only changes
+                                            if [ -n "$diff_output" ]; then
+                                                filtered_diff=$(filter_hash_only_diffs "$diff_output" || true)
+
+                                                if [ -n "$filtered_diff" ]; then
                                                     echo -e "      ${YELLOW}$relpath:${NC}"
-                                            diff -u "$old_file" "$file" 2>/dev/null | head -50 | tail -n +3 | sed 's/^/        /' || true
+                                                    echo "$filtered_diff" | sed 's/^/        /'
+                                                fi
+                                            fi
                                         fi
                                     fi
-                                done < <(find "$new_path" -type f -name "$pattern" 2>/dev/null | head -20)
                                 done
+                            fi
                         # If it's a file, diff it directly
                         elif [ -f "$old_path" ] && [ -f "$new_path" ]; then
                             if file "$new_path" | grep -q "text"; then
-                                diff -u "$old_path" "$new_path" 2>/dev/null | head -50 | tail -n +3 | sed 's/^/      /' || true
+                                # Get diff output
+                                diff_output=$(diff -u "$old_path" "$new_path" 2>/dev/null | head -50 | tail -n +3 || true)
+
+                                # Filter hash-only changes
+                                if [ -n "$diff_output" ]; then
+                                    filtered_diff=$(filter_hash_only_diffs "$diff_output" || true)
+
+                                    if [ -n "$filtered_diff" ]; then
+                                        echo "$filtered_diff" | sed 's/^/      /'
+                                    else
+                                        echo "      (only hash changes)"
+                                    fi
+                                fi
                             else
                                 echo "      (binary file)"
                             fi